Mechanical stop device



March 18, 1947. MEAD ETAL 2,417,434

MECHANICAL STOP DEVICE Filed Feb. 15 1945 5 Sheets-Sheet 1 FIG/ 45 42 a [a 30 2/ I6 20 3/ .39 4/ l4 40 2.? 1 22 24 4 a r O a 2 :4 k .25 46 .32 /7 a a: 47

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E. 0. MEAD INVQVTORSEM THOMAS ZTTORNEY March 18, 1947.

E. D. MEAD ETAL MECHANICAL STOP DEVICE I5 Sheets-Sheet 2 Filed Feb. 13,1945

' FIG. 4

'EQM EAD INVENTORSEM ATTORNEY Patented Mar. 18, 1947 UNITED STATES PATENT OFFICE Edward D. Mead, Caldwell, and Frank M.

Thomas, Summit, N. J., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 13, 1945, Serial No. 577,631

6 Claims.

This invention relates to mechanical stop devices and more particularly to a mechanical device for stopping the rotation of shafts.

The object of the present invention is to provide an improved means for stopping the rotation of a shaft in accordance with a predetermined program or setting.

A feature of the invention resides in the use of a single spring means in the stop device for cushioning the stopping action of a traveler positioned on a rotatable threaded shaft.

Another feature of the invention is the provision of an adjustable means for controlling the operation of the traveler within prescribed limits.

A further object of the invention is the provision of means on the traveler for controlling the operation of electrical switches associated there with.

The device of this invention provides a means whereby a gradually increasing spring load, provided by a single helical spring, may be applied to a rotatable member in accordance with a predetermined program or setting. For example, the device may be used in gradually stopping the rotatable shaft of a potentiometer or the like to which it is operatively connected, before the wiper contact of the potentiometer operated by the shaft of the potentiometer, nears the end of a resistance winding or approaches a fixed stop thereon. 1

The invention also contemplates the control of the motor driving the shaft which in turn drives the apparatus connected thereto by not only mechanically stopping the rotation of the shaft and its associated gears, etc., but by also shutting off the electrical current to the motor and in some instances stopping the shaft and reversing the motor to cause the traveler to move in the opposite direction.

Means is also provided for indexing and predetermining the amount of travel on the threaded shaft of the traveler member mounted thereon, said means being provided with numerals thereon which may be calibrated with respect to the pitch of the threaded member and also the diameter thereof, to provide a substantially micrometer adjustment to the stop so as to limit within very close margins the amount of travel of the traveler on the threaded shaft.

The invention will be more clearly understood from the following detailed description when read with reference to the following drawings in which:

Fig. 1 is a side elevational view of the stop device of this invention;

Fig. 2 is a view similar to Fig. 1 with parts thereof shown in cross-section;

Fig. 3 is an exploded view of the principal portion of the device shown in Figs. 1 and 2;

Fig. 4 is a side elevational view of the device of this invention, employed to control the operation of suitable electrical switches;

Fig. 5 shows a modified type of electrical switching arrangement which may be operated by the device of this invention; V

Fig. 6 is a view similar to Fig. 1 except that the traveler of the device has been shifted to the right tends some distance beyond the support l2 and is 7 provided with a gear member M which is driven by means of the pinion l5 which may be driven in any suitable manner.

Mounted on the threaded shaft I3 is a traveler member l6 wh ch when the shaft is rotated will traverse either to the right or to the left depending upon the direction of rotation of the shaft l3.

As shown in Fig. 2 and more in detail in Fig. 3, the traveler member #6 comprises an internally threaded sleeve member I! in engagement with the threaded shaft l3 and is provided at each end with a reduced diameter portion to provide shoulder portions, said reduced diameter portions being provided with external threads. Located on the main body portion of the sleeve I1 is a helical spring l8 each end of which extends outwardly a short'distance at right angleswith respect-to the convolutions of the spring. Positioned on the shoulder'portions of the, sleeve l1 and located on each end thereof are the washer members l9 and 20 each of which are cut away on their peripheries at 21 and 22 toprovjide recesses for accommodating the ends 23 and 24 of the spring I6 and to provide stops for definitely limiting the amount of travel of said spring ends, when said spring is tensioned beyond the amount initially set, which will be described more in detail later on in the specification.

The washer I9 is provided with a key-way 25 which is adapted to engage the key 25 located'on the shoulder portion of the sleeve l1 toeifect mechanical connection therebetween and due to the extending bifurcated portion 21 of the washer l9, which is in engagement with the longitudinally extending rod 28, the rotation of the sleeve H willbe prevented when the spring I8 is tensioned by turning it in a clockwise direc tion either initially or later on within the limits of the recesses 2| and 22 as heretofore described.

The washer 20 is provided with a plurality cf key-ways 29, any one of which may be adapted to engage the opposite end of the key 26 which extends the length of the sleeve l1 and projects beyond the surface of the shoulder adjacent said washer. This permits the recess 22 to be positioned with respect to any of the apertures in the washer 3|. Thus an initial tension may be applied to the spring [8 by locating the end 24 of sleeve H with one of the desired keyways 29 in engagement with the end of the key .26 adjacent said washer 20. The washers 30 and 3| are each provided with extending ear portions 32 and 33 and are held in intimate contact with the washers l9 and 29 by means of the threaded collars 34 and 35 which pass through the bores of the washers 30, i9 and 4 hereinafter described with respect to the operation of the device. 7 I I In Fig. 4 there is shown mounted on the traveler IS a projecting arm 48 which is adapted to engage arms 49 and 50 of the microswitches 5| and 52. These switches may be utilized to.con-

trol any desired electrical circuit, for example,

they maybe used to controlthe operation and direction of rotation of the driving motor 53.

In Fig. 5 there is shown an arrangement wherein an arm 54 mounted on the traveler will engage in a definite sequence of operation the micro switches 55, 56 and 51. These switches may be connected to any electrical circuit where- 'in it is desired to control electrical apparatus in a definite sequence of operation.

In the operation of the device as heretofore described, the arm 21 of the traveler It is set at the scribe mark 44 on the shaft 28. This indicates that the traveler I6 is substantially centrally located with respect to its travel either to the right or to the left. The next step after it has been determined the distance the traveler is to travel in each direction, to perform the function desired, is to loosen the set screwsdiiand ii of the nuts 38 and 39. The loosening of theseset screws willpermit the nuts to be moved along the shaft l3 to the desired position where they are secured against movement by tightening the set screws 66 and 4|. The dial 42 associated with V nut 38 is then moved up into engagement there- :20, 3| thereby threadedly engage the reduced dia'meter portions 36 and 31 .of the sleeve i1 and firmly clamp the component parts of the travjeler unit it together. 1 Located on the threaded shaft I3 on each side of the traveler member it are the internally threaded slotted nuts 38 and 39. These nuts act as stop members for the traveler l6 and may be positioned along the shaft I3 by simply loosening the setscrews 40 and 4|, which pass through the slotted portion thereof, rotating the nuts with respect to the shaft which will cause them to travel either to the right or the left and then locking them to the shaft by tightening the set screws 40 and 4| which causes the nuts to firmly grip the, threaded shaft due to their slotted configuration. Itvwill be observed that the nut 38 has associated therewith a dial member 42; which has associated with it a pointer 53. This arrangement provides an indexing means for obtaining a predetermined setting of the nuts 38 and 39 with respect to the traveler I6 which has associated therewith an initial setting scribe mark 44 located on the shaft 28 which is intended to register with the end of the bifurcated portion 21 of the traveler l6. Thus when the traveler arm 12-1 coincides with the scribe mark, the nut 38 may be positioned with respect thereto and the dial t2 firmly clamped thereagainst by means of a nut 45.

Each of the nuts 38 and39 is provided with lugs or bosses 46 and 4'! which are adapted to engage the ears 32 and 3.3, respectively, on the washers 3B and Si depending upon the direction of travel, when the traveler I 6 has reached the end of its travel, which will cause the traveler to stop with a cushioning effect due to the tensioning of the spring l8, the action of which will be with and secured thereagainst by means of the nut 45 with the pointer .43 registering with the 00 mark on the dial.

Thus when the shaft I3 is it will traverse the shaft. For example, when the shaft is rotated clockwise it will cause the traveler IE to move to the right. When thelug s 33 on the traveler I6 engages the lug 46 on the rotating nut 39, it will cause the spring l8 to'be wound up or further tensioned inasmuch as the washer 3| which carries the lug 33 will be caused to rotate in a clockwise direction. This will cause the end 24 of the spring l8 which is located in one of the apertures in said washer to travel clockwise and further tension the spring Hi. The limit of travel of the end 24 of the spring l8'is controlled by the recess 22 which is approximately one-quarter of the circumference of said wash- In a similar manner when theshaft I3 is rotated counterclockwise the lug 46 on the nut 38 will engage the lug 32 on the washer 3B andthe sequence of operation described above with respect to the clockwise rotation of .the shaft will likewise occur at this time.

The initial tension of the spring it may be set as desired by means of the washer 20 and the apertures in the washers 30 and 3|.' This initial tension is important since the initial tension and the build-up of the springhas to be considered with respect to the kinetic energy of the system which has to be stopped.

While we have shownand described herein th preferred embodiment of our invention it is to be understood that various changes and modifications may be made'therein without departing from the spirit of the invention andwe only intend to be limited by the scope of the appended claims.

What is claimed is:

rotated the traveler 1. A device for mechanically stopping the retation of a shaft which comprises supporting means, a threaded shaft journaled therein, means connected to said shaft for imparting a rotating motion thereto, a traveler member threadedly mounted on said shaft and movable longitudinally therealong by the rotating motion thereof, stops on said shaft for limiting the amount of longitudinal movement of said traveler, and shock-absorbing meanson said traveler engageable with said stops for cushioning the stopping action of said traveler.

2. A device for mechanically stopping the rotation of a shaft which comprises supporting means, a threaded shaft journaled therein, means connected to said shaft for imparting a rotating motion thereto, a traveler member threadedly mounted on said shaft and movable longitudinally therealong by the rotating motion thereof, adjustable stops on said shaft for limiting the amount of longitudinal movement of said traveler, and adjustable shock-absorbing means on said traveler engageable with said stops for cushioning the action of said traveler.

3. A device for mechanically stopping the rotation of a shaft which comprises supporting means, a threaded shaft journaled therein, means connected to said shaft for imparting a rotating motion thereto, a traveler member threadedly mounted on said shaft and movable longitudinally therealong by the rotating motion thereof, stops on said shaft for limiting the amount of longitudinal movement of said traveler, and shock-absorbing means on said traveler including a helical spring and engageable with said stops for cushioning the stopping action of said traveler.

4. A device for mechanically stopping the rotation of a shaft which comprises supporting means, a threaded shaft journaled therein, means connected to said shaft for imparting a rotating motion thereto, a traveler member threadedly mounted on said shaft and movable longitudinally therealong by the rotating motion thereof, stops on said shaft for limiting the amount of longitudinal movement of said traveler and shock-absorbing means on each end of said traveler including a single helical spring and engageable with said stops for cushioning the stopping action of said traveler.

5. A device for mechanically stopping the rotation of a shaft which comprises supporting means, a threaded shaft journaled therein, means connected to said shaft for imparting a rotating motion thereto, a traveler member threadedly mounted on said shaft and movable longitudinally therealong by the rotating motion thereof, adjustable stops on said shaft for limiting the amount of longitudinal movement of said traveler, adjustable shock-absorbing means including a helical spring on said traveler engageable with said stops for cushioning the stopping action of said traveler, switches adjacent said traveler, and an arm on said traveler, engageable with said switches for controlling the opening and closing thereof.

6. A device for mechanically stopping the rotation of a shaft which comprises supporting means, a threaded shaft journaled therein, a motor connected to said shaft for imparting a rotating motion thereto, a traveler member threadedly mounted on said shaft and movable longitudinally therealong by the rotating motion thereof, adjustable stops on said threaded shaft for limiting the amount of longitudinal movement of said traveler, adjustable shock-absorbing means including a helical spring on said traveler engageable with said stops for cushioning the stopping action on said traveler, switches adjacent said traveler and an arm on said traveler engageable with said switches for controlling the operation of said motor.

EDWARD D. MEAD. FRANK M. THOMAS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,788,302 Hummel Jan. 6, 1931 2,252,796 Whittell Aug. 19, 1941 1,283,386 Wenzelmann Oct. 29, 1918 702,275 Arnold June 10, 1902 992,226 McDonald May 16, 1911 2,348,987 Lock May 16, 1944 

